BiffVernon Blogspot

Monday, February 04, 2013

Butterfly
Conservation. State of Britain’s Larger Moths 2013

Britain's leading butterfly and moth conservation organisation, Butterfly Conservation, published on the 1st of February a 30-page report on moths.

The report gives us a sad
picture: “Across Britain, the total abundance of larger moths declined
significantly, by 28%, during the 40-year period from 1968 to 2007.”

Looking beyond the actual state of moth populations, we must search for reasons for the decline.

“Several studies have shown
higher abundance and species richness of moths associated with lower intensity
farming practices implemented as part of organic conversion, agri-environment
schemes or experimental treatments. In particular, moths benefit from the
presence of field margins and boundary features, including mature trees.
Conversely, we might assume that the general intensification of agricultural
management that has taken place since the 1950s, which has included widespread
loss of hedgerows, boundary trees and botanically-rich field margins, as well
as the intensive use of pesticides, will have impacted negatively on moths.”Climate change is
discussed at length, but this cannot explain the decline, indeed it is likely
that warming has allowed the northerly spread of some species. “Climate Change…seems to have had
both positive and negative effects.”A paragraph is devoted to
light pollution but concludes that “…we do not know whether the massive
increase in background light levels in Britain has made any contribution to the trends reported
here.”

“Habitat changes,
especially those related to agricultural intensification, changing woodland
management and urbanisation, appear to have had substantial, largely negative
impacts on moths.”

Of course habitat must be
key, but we need to look closely, beyond that which can be seen with the
eye. In my area, eastern Lincolnshire, I have noticed a dramatic loss of moths in just
the last 10 years, as evidenced by splat numbers when driving at night. My anecdotal impression is that the decline has been
much greater than the 28% figure in the report.
However, in my neighbourhood at least, there has not been an apparent habitat loss; instead there has
been a lot of tree planting and leaving of arable field margins and conservation minded management of watercourses over the same
period. The missing piece from the
report is any serious consideration of pesticides. There is just the one mention, part of the
longer sentence from page 19, quoted
above, “…as well as the intensive use of pesticides.” And no mention of neonicotinoids. This is particularly surprising in the light
of the current public debate about neonicotinoids impacting on bee populations. Accumulating scientific research has now led
the EU Commission towards introducing legislative controls.Why does the Report duck
what is likely to be the most significant issue, completely?